Revenue Recognition (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Jul. 20, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Disaggregation of Revenue [Abstract]
Total net sales		$ 272,528	$ 301,909	$ 597,981	$ 620,310
Contract liability						$ 2,757
Pellet Plant [Member]
Disaggregation of Revenue [Abstract]
Total net sales				143,300
Pellet Plant [Member] | Subsequent Event [Member]
Disaggregation of Revenue [Abstract]
Agreement liability amount expected to pay to customer	$ 68,000
Number of days required for payment agreement amount	120 days
Forgiveness of accounts receivable	$ 7,315
Pellet Plant Agreement Sale Charge [Member]
Disaggregation of Revenue [Abstract]
Total net sales		(75,315)
Domestic [Member]
Disaggregation of Revenue [Abstract]
Total net sales		203,386		473,464
Domestic [Member] | Equipment Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		202,624		388,368
Domestic [Member] | Pellet Plant Agreement Sale Charge [Member]
Disaggregation of Revenue [Abstract]
Total net sales		(75,315)		(75,315)
Domestic [Member] | Parts and Component Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		59,059		129,321
Domestic [Member] | Service and Equipment Installation Revenue [Member]
Disaggregation of Revenue [Abstract]
Total net sales		5,179		9,529
Domestic [Member] | Used Equipment Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		2,804		6,007
Domestic [Member] | Freight Revenue [Member]
Disaggregation of Revenue [Abstract]
Total net sales		6,745		13,923
Domestic [Member] | Other [Member]
Disaggregation of Revenue [Abstract]
Total net sales		2,290		1,631
International [Member]
Disaggregation of Revenue [Abstract]
Total net sales		69,142		124,517
International [Member] | Equipment Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		44,500		77,504
International [Member] | Parts and Component Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		19,660		37,483
International [Member] | Service and Equipment Installation Revenue [Member]
Disaggregation of Revenue [Abstract]
Total net sales		1,201		2,326
International [Member] | Used Equipment Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		1,874		3,233
International [Member] | Freight Revenue [Member]
Disaggregation of Revenue [Abstract]
Total net sales		1,808		3,656
International [Member] | Other [Member]
Disaggregation of Revenue [Abstract]
Total net sales		99		315
Infrastructure Group [Member]
Disaggregation of Revenue [Abstract]
Total net sales		83,202		230,296
Infrastructure Group [Member] | Domestic [Member]
Disaggregation of Revenue [Abstract]
Total net sales		65,072		199,558
Infrastructure Group [Member] | Domestic [Member] | Equipment Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		102,724		188,242
Infrastructure Group [Member] | Domestic [Member] | Pellet Plant Agreement Sale Charge [Member]
Disaggregation of Revenue [Abstract]
Total net sales		(75,315)		(75,315)
Infrastructure Group [Member] | Domestic [Member] | Parts and Component Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		29,269		70,382
Infrastructure Group [Member] | Domestic [Member] | Service and Equipment Installation Revenue [Member]
Disaggregation of Revenue [Abstract]
Total net sales		3,283		5,211
Infrastructure Group [Member] | Domestic [Member] | Used Equipment Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		1,384		3,009
Infrastructure Group [Member] | Domestic [Member] | Freight Revenue [Member]
Disaggregation of Revenue [Abstract]
Total net sales		3,216		7,254
Infrastructure Group [Member] | Domestic [Member] | Other [Member]
Disaggregation of Revenue [Abstract]
Total net sales		511		775
Infrastructure Group [Member] | International [Member]
Disaggregation of Revenue [Abstract]
Total net sales		18,130		30,738
Infrastructure Group [Member] | International [Member] | Equipment Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		12,040		17,955
Infrastructure Group [Member] | International [Member] | Parts and Component Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		4,310		9,372
Infrastructure Group [Member] | International [Member] | Service and Equipment Installation Revenue [Member]
Disaggregation of Revenue [Abstract]
Total net sales		644		1,457
Infrastructure Group [Member] | International [Member] | Used Equipment Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		661		1,164
Infrastructure Group [Member] | International [Member] | Freight Revenue [Member]
Disaggregation of Revenue [Abstract]
Total net sales		429		683
Infrastructure Group [Member] | International [Member] | Other [Member]
Disaggregation of Revenue [Abstract]
Total net sales		46		107
Aggregate and Mining Group [Member]
Disaggregation of Revenue [Abstract]
Total net sales		116,297		235,364
Aggregate and Mining Group [Member] | Domestic [Member]
Disaggregation of Revenue [Abstract]
Total net sales		78,893		162,730
Aggregate and Mining Group [Member] | Domestic [Member] | Equipment Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		57,989		121,483
Aggregate and Mining Group [Member] | Domestic [Member] | Pellet Plant Agreement Sale Charge [Member]
Disaggregation of Revenue [Abstract]
Total net sales		0		0
Aggregate and Mining Group [Member] | Domestic [Member] | Parts and Component Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		18,311		36,145
Aggregate and Mining Group [Member] | Domestic [Member] | Service and Equipment Installation Revenue [Member]
Disaggregation of Revenue [Abstract]
Total net sales		564		890
Aggregate and Mining Group [Member] | Domestic [Member] | Used Equipment Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		652		2,063
Aggregate and Mining Group [Member] | Domestic [Member] | Freight Revenue [Member]
Disaggregation of Revenue [Abstract]
Total net sales		1,912		3,720
Aggregate and Mining Group [Member] | Domestic [Member] | Other [Member]
Disaggregation of Revenue [Abstract]
Total net sales		(535)		(1,571)
Aggregate and Mining Group [Member] | International [Member]
Disaggregation of Revenue [Abstract]
Total net sales		37,404		72,634
Aggregate and Mining Group [Member] | International [Member] | Equipment Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		23,385		45,712
Aggregate and Mining Group [Member] | International [Member] | Parts and Component Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		12,070		22,359
Aggregate and Mining Group [Member] | International [Member] | Service and Equipment Installation Revenue [Member]
Disaggregation of Revenue [Abstract]
Total net sales		328		640
Aggregate and Mining Group [Member] | International [Member] | Used Equipment Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		630		1,486
Aggregate and Mining Group [Member] | International [Member] | Freight Revenue [Member]
Disaggregation of Revenue [Abstract]
Total net sales		967		2,297
Aggregate and Mining Group [Member] | International [Member] | Other [Member]
Disaggregation of Revenue [Abstract]
Total net sales		24		140
Energy Group [Member]
Disaggregation of Revenue [Abstract]
Total net sales		73,029		132,321
Energy Group [Member] | Domestic [Member]
Disaggregation of Revenue [Abstract]
Total net sales		59,421		111,176
Energy Group [Member] | Domestic [Member] | Equipment Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		41,911		78,643
Energy Group [Member] | Domestic [Member] | Pellet Plant Agreement Sale Charge [Member]
Disaggregation of Revenue [Abstract]
Total net sales		0		0
Energy Group [Member] | Domestic [Member] | Parts and Component Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		11,479		22,794
Energy Group [Member] | Domestic [Member] | Service and Equipment Installation Revenue [Member]
Disaggregation of Revenue [Abstract]
Total net sales		1,332		3,428
Energy Group [Member] | Domestic [Member] | Used Equipment Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		768		935
Energy Group [Member] | Domestic [Member] | Freight Revenue [Member]
Disaggregation of Revenue [Abstract]
Total net sales		1,617		2,949
Energy Group [Member] | Domestic [Member] | Other [Member]
Disaggregation of Revenue [Abstract]
Total net sales		2,314		2,427
Energy Group [Member] | International [Member]
Disaggregation of Revenue [Abstract]
Total net sales		13,608		21,145
Energy Group [Member] | International [Member] | Equipment Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		9,075		13,837
Energy Group [Member] | International [Member] | Parts and Component Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		3,280		5,752
Energy Group [Member] | International [Member] | Service and Equipment Installation Revenue [Member]
Disaggregation of Revenue [Abstract]
Total net sales		229		229
Energy Group [Member] | International [Member] | Used Equipment Sales [Member]
Disaggregation of Revenue [Abstract]
Total net sales		583		583
Energy Group [Member] | International [Member] | Freight Revenue [Member]
Disaggregation of Revenue [Abstract]
Total net sales		412		676
Energy Group [Member] | International [Member] | Other [Member]
Disaggregation of Revenue [Abstract]
Total net sales		$ 29		$ 68